Field of the Invention
The present invention relates to sorptive substrates. More specifically, the invention relates to an integrated process for treating and packaging sorptive substrates used for contamination control, and an integrated system for preparing wipers for use in a cleanroom environment.
Technology in the Field of the Invention
Cleanrooms are used in various settings. These include semiconductor fabrication plants, pharmaceutical and medical device manufacturing facilities, aerospace laboratories, and similar places where extreme cleanliness is required.
Cleanrooms are maintained in isolated areas of a building. In this respect, cleanrooms typically have highly specialized air cooling, ventilation and filtration systems to prevent the entry of air-borne particles. Individuals who enter a cleanroom will wear special clothing and gloves. Such individuals may also use specialized notebooks and writing instruments.
It is desirable to clean equipment within a cleanroom using a sorptive substrate. For example, in semiconductor fabrication cleanrooms, surfaces must be frequently wiped. In doing so, special wipes (or wipers) and cleaning solutions are used in order to prevent contamination. For such applications, the wipers themselves must also be exceptionally particle-free, and should have a high degree of wet strength and structural integrity. In this way, the wiper substrates do not disintegrate when used to wipe surfaces, even when dampened by or saturated with a cleaning liquid.
Products used in sensitive areas such as semiconductor fabrication cleanrooms and pharmaceutical manufacturing facilities are carefully selected for certain characteristics. These include particle emission levels, levels of ionic contaminants, adsorptiveness, and resistance to degradation by wear or exposure to cleaning materials. The contamination which is to be controlled is often called “micro-contamination” because it consists of small physical contaminants. Such contaminants include matter of a size between that of bacteria and viruses, and chemical contaminants in very low concentrations, typically measured in parts per million or even parts per billion.
The micro-contaminants are usually one of several types: physical particles, ions and microbials, and “extractables.” Extractables are impurities leached from the fibers of the wiper. Previously, The Texwipe Company of Upper Saddle River, N.J. (now Texwipe, Division of Illinois Tool Works of Kernersville, N.C.) has developed wipers especially suited for use in particle-controlled environment. See, e.g., U.S. Pat. No. 4,888,229 and U.S. Pat. No. 5,271,995, each to Paley, et al., the disclosures of which are incorporated herein by reference in their entireties to the extent permitted by law. See also U.S. Pat. No. 5,229,181 to Daiber, et al., also incorporated herein by reference to the extent permitted by law. These patents disclose wipers for cleanroom use.
However, a need exists for an improved process for preparing absorbent and adsorbent substrates having a consistently high degree of cleanliness. In addition, a need exists for a cleaning system to generate cleanroom wipers consistently and efficiently. Further, a need exists for an integrated processing and packaging system for cleanroom wipers that operates without need of human intervention following start-up.